Measured-service telephone system



T. G. MARTIN. I MEASURED SERVICE TELEPHONE SYSTEM.

APPLICATION FILED 050.24. 1911.

1 ,350 87 5 V Patented Aug. 24, 1920.

fnuanlm" Til/J52 E a'rZLn HZZUrnEy UNITED STATES PATENT OFFICE.

TALBOT G. MARTIN, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRICCOMPANY, OF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

MEASURED-SERVICE TELEPHONE SYSTEM.

Application filed December 24, 1917.

To all u /mm it may concern:

Be it known that I, TALBOT MARTIN, a, citizen of the United States ofAmerica, and resident of Chicago, Cook county, Illinois, have inventedcertain new and useful Improvements in Measured-Service TelephoneSystems, of which the following is a specification.

My invention relates to automatic telephone systems. It relates morespecifically to improvements in automatic switches for such systems andto improved means for registering calls in an automatic system.

In a telephone system'it is of considerable value to the operatingcompany to be able to inform a subscriber as to the number of times hisline has been called while busy. For instance where an ofiice has onlyone telephone and a number of calls come in which are lost by reason ofthe said tele phone being in use, the company can more easily persuadethe subscriber that another instrument should be installed it they cangive him accurate information as to just how many calls were turned awaywhen his telephone was busy. In order to obtain this information a metermust be provided to register such busy calls.

My invention provides such a nieter and is shown in connection withautomatic switches of a well known type, it being understood, however,that I do not wish to limit myself to the exact type of switches shown,but that such an arrangement may be provided in connection with any wellknown type of switches without departing from the spirit of myinvention.

To accomplish the foregoing and other useful ends my invention relatesto matters hereinafter more specifically set forth and claimed.

In the accompanying drawing I have illustrated an established connectionbetween calling subscriber A and called subscriber B. Associated with,and individual to the calling subscribers line is shown a line switch Cof the plunger type shown in British Patent to Martin #1419 of 1910.which has access to a number of trunk lines leading to connectorswitches, similar to that shown at D, which are in turn operated toconnect with and signal any called subscriber.

Although I have shown my 1nvent1on 1n Specification of Letters Patent.

Serial No. 208,579.

connection with a one hundred line system it will be understood that thecapacity of the exchange may be increased by inserting one or moreselectors of the well known Strowger type between the line switch C andthe connector D.

I will now e:;lain more in detail how a connection may be extended froma calling to a called subscribers line and how when connection is madewith a called line which is busy, a special meter provided for thatpurpose will operate to register the call.

hen the subscriber A removes his receiver to initiate a call he closesan energizing circuit for the line relay 2 of line switch C as follows;from ground G through springs 3 and 4, line conductor 5, transmitter 6,receiver 7, calling device springs 8, hook switch springs 9 and 10, lineconductor 11, springs 12 and 13, and through relay 2 to battery B. Linerelay 2 energizes and closes a circuit for the pull down coil 16 fromground G through the springs M and 15, and said winding 16, to battery.l he pull down winding 16 thereupon energizes to disconnect the linerelay 2 and ground G from the line conductors 5 and ll'by means of thearmature 65 and also operates the plunger (not shown) to force intocontact in pairs the springs 17 and 18, 19 and 20, 21 and 22, and 23 and24. The closure of springs 17 and 18 and 23 and 24: extends the lineconductors 5 and 11 to the conductors leading to connector D. It is tobe understood that the usual master switch is user. in a system of thischaracter and operates to always maintain an idle connector switchDaccessible to the line switch C, and also that although only one set ofsprings 17- 2%- is shown, each line switch is provided with a setforming the terminal of a trunk line leading to a connector switch D.The extension of the line conductors 5 and 11 as explained the trunkline leading to con nector D causes an energizing circuit to be closedfor the D which extends over the conductors 5 and 11 and through thesubstation A. The relay 26 ,upon energizing closes a circuit for theslow acting relay 2? from ground G through springs 28 and 29 and throughrelay 2'? to battery B Relay 27 thereupon energizes anal closes aholding circuit for the holding Patented Aug. 24, 1920.

plurality of such sets, each winding of line switch C through springsfrom ground G The relay 2 of the line switch U being slow-acting, doesnot allow its armature 14 to fall back as soon as its circuit is openedby the pull down coil 16,

but maintains the circuit of the winding 16 closed at springs 14 and 15until the above 7 The calling subscriber now operates his dial inaccordance with the first digit of the called subscribers number therebyopening the circuit of the line relay 26 a corresponding number of timesby separating the springs 8 of his dial. The relay 26 thereupondeenergizes a number of t1mes and each time the armature cuit' is closedfor the vertical magnet 32 and relay 34 in series to step the wipers35-7-38, inclusive, up to a certain level of the connector bank in whichare located the terminals leading to the desired subscribers line. Thecircuit-for the vertical magnet may be traced irom ground G springs 28and 39, springs 33, relay 34, vertical magnet 40 in first position to32, and side switch battery. As soon as the wipers are raised one stepby the operation, of the vertical magnet the ofi normal springs areoperated to close the circuit of the release magnet 31 at springs 43 andto close a circuit for the meter relay 52 at the springs 42. Theenergization of the relay 52 at this time is without effect as thecircuit for the meter F is held open at the springs 77 of the busy relay51. However, relay 52 closes apair of springs 78, which are in serieswith the meter F of the called substation but which circuit is now openat the wiper 37 and which is also open at another point at the springs77 of relay 51. Relay 34 being a slow acting relay will maintain itsarmature 44 in attracted position as, long as relay 26 is operating inresponse to impulses, thereby closing a circuit for the private magnet48 from ground through springs 44 and 45, and the said private magnet 48to battery. As soon as the impulses for the first digit cease however,the relay'26 willremain in its attractor position and relay 34 will fallback, thereby opening the circuit for the private magnet 48 and throughthe deenergization of said private magnet, causing the side switchwipers 40 and 41 to pass to second position in a well known manner,substituting the rotary magnet 47 to the control of the line relay 26 inplace of the vertical magnet 32..

Relay 27 also opens a contact 28 falls back a cir-.

63, side switch wiper 40, to battery.

The calling subscriber may now operate his dial for the second digit ofthe called number by separating the springs 8 of his calling device anumber of times, the line relay 26 in response tothe impulses for thisdigit again falls back a corresponding number of times and upon eachdeenergization, closes a circuit for the rotary magnet 47 and the slowrelay 34 in series. This circuit may be tracedji'rom ground G throughsprings 28 and, 39, relay 34, springs 46, rotary magnet 47,- and sideswitch wiper 40 (in second position) to battery. The rotary magnet 47operates in'response to the im pulses over the above circuit to rotatethe wipers 35-38 inclusive, around to the contacts of the bankcorresponding to the desired line and the relay 34 also operates toagain close the circuit of the private magnet. Assuming that the calledline is idle and there is no ground on the contact upon to the privatewiper 38, to guard the called,

line against seizure and also to close an energizing circuit for thebridge cut-ofi" winding 25 of the line switch 0' to disconnect the linerelay 2 and ground from the called line in the usual manner.

The side switch wiper 40 upon passing to third position supplies batteryto the other end of relay 63, which relay energizes at this time toconnect the ringing generator with the called line.

The circuit of the relay 63 may be traced from ground G side switchwiper 41, relay Relay 63 upon energizing closes the springs 68 and 69 tosignal the called subscriber and also opens a pair of springs in thecircuit of the meter relay 52 which relay thereupon deenergizes.

As soon as the line circuit is cut through by relay 63 the calledsubscribers bell is operated over a circuit extending from battery Bthrough the upper winding of relay 54, springs 66 and 67, springs 68,wiper to and through the bell of substation 1%, wiper 36, springs 69,springs 70 and T1,

' through the contacts of an interrupter relay transmitter and receiverfor the bell and condenser at the telephone of substation B.

elay 54 then energizes over the above traced circuit and locks itself toground -at off normal springs 42 and through its own springs 74 and itslower winding to battery B Relay 54 upon energizing also disconnects theleads from the interrupter relay armature and its own upper winding fromthe called line to out be the ringing current and also cuts the lineconductors from the calling station through to the called line.

The called subscriber now receives talking batterythrough the twowindings of the back bridge relay 53 and conversation may be carried onover the talking circuit which is shown by heavy conductors. v i

The release of the connection is controlled by the opening of the linecircuit at the springs 9 and 10 of the calling station when the calledsubscriber restores his receiver. This opening of the line circuitcauses the line relay 26 of the connector D to fall back to in turn openthe circuit of slow aetin release relay Relay 2? then falls back,closing a circuit for the release magnet 31 at the back contact of itsupper springs and opening the holding circuit for the switching relav 25of theline switch C. The entire apparatus is thereby restored to nor-"mal inthe usual manner and the circuit of the release magnet 31 isopened at springs 43 when the shaft reaches normal position.'

I will now explain hoW the meter F is operated: Assuming that the calledline is busy when an attempt is made to establish connection therewitheither by reason of its being called orfmaking a call, there will beaground potentialon the private normal contact with which the wiper 38makes connection. Now as soon asthe impulses for the second or lastdigit of. the called number cease and before the private magnet has beendeenergized by the falling back of slow relay 84, a circuit will remainclosed for a moment from the private wiper 38 through the 'sideswitchwiper 41 (in second position) and relay 51 to the spring 49 of relay 34.Now when the relay 34 falls back after the cessation of impulses, theprivate magnet will not 'deenergiz'e but will be held energized over theabove traced circuit from ground on the private wiper, through sideswitch wiper 41 (in second position) springs 50 and 55, relay 51,springs 49 and 45, and

private magnet 48 to battery, .As the spring 45 makes contact withthespring 49 before disengaging from the spring 44 it will be seen that theprivate magnet circuit is not opened and that the side switch wipers 40and 41 will be held in second position. Relay 51 also energizes inseries with magnet 48 and closes a locking circuit 'foritself throughsprings 55 and 56 and the off normal springs 42 to ground, and alsocloses thesprings 76 to supply busy signaling current from the busymachine H to the calling line to inform the calling subscriber that thecalled for line is busy. The energization of relay 51 also closesanother point in the circuit of the meter F at the springs 77 and alsoopens the circuit of the meter relay 52at the springs 79 and opens thecircuit of the rotary magnet at the springs 46. The relay52 is slowacting and although its energizing circuit is broken at the springs 79,it maintainsits armature in attracted position, long enough to send amomentary impulse of current to the meter F over the following circuit:From ground through springs '42, springs 77, springs 78, wiper 37, andthrough the meter F to battery. A moment'after its circuit is opened atthe springs 79, the relay 52 deenergizes to open the circuit of themeter F at the springs 7 8. It will be seen therefore, that the meter F01)- erates only once for each call to a busy line and that the switchthen remains locked on the busy line until released in the usual mannerby the hanging up of the receiver at the calling station. Also it willbe seen that, as the meter F only receives a momentary impulse ofcurrent each time a connector lands on the busy line to which it isattached, any number of connectors may call this busy line at frequentintervals and even though one of said switches remains locked'on saidline for a length of time, still the meter will be free after eachmomentary impulse to receive another charge from another connector.

It will be seen therefore, that I have devised a very simple andefiicient method of metering calls to a busy line, at the same timemaking it impossible for said meter to be operated more than once forthe establishment. of a single connection.

What I claim as my invention is: 1. In a telephone system, subscriberslines, means for extending a connection from a calling to a called oneof said lines,

said called line is busy.

2. In a telephone system, a subscribers line, means for making said linebusy to calls from other subscribers, a meter for said line, and meansfor operating said meter when another subscriber attempts to establish aconnection with said busy line.

3. In a, telephone system, a subscribers line, means for making saidline busy to calls from other subscribers, a meter for said line, andmeans for op'eratingsaid meter each time another subscriber attempts toestablish a connection with said busy line.

4. In a telephone system, a subscribers 5.. In a: telephone system, asubscribers line, means for making. said line busy, a

connector switch, means for. operating said connector switch to testsaid subscribers line; a .meter for said line, and means con 7 trolledbysaid. connector switch for operating said meter when the line istested and found busy.

6. In a telephone system, a subscribers line, means for making said linebusy, a

connector switch, means for operating said connector switch to test saidsubscribers line, means and found busy.

line,-a meter forsaid line, and a quick and slow relay in said connectorswitch for operating said meter when the line s tested 7. In a telephonesaid line, a connector switch, means for operating said connector switchto test said subscribers line, a meter for said line, and

' means controlled by said connector switch I 7 tested and "foundbusy.

,line',-means for making said line busy when l line a v r V a v meterfor said line tor registering the number of calls made to said line whenbusy, a

circuit for said meter, and quick and slow line, a 1116i6I" for saidline,

switchesfmeans for operating one of said a quick and slow for operatingsaid meter when the line is c 8. In a telephone system, a subscr'ibers aconnection is entended either to or from said line, a connector switch,means for operating saidconnector switch to test said. tor said line,and relay in said connector switch for operating said meter when the;

subscribers line a meter line ist'ested and found busy. v

9. In a telephone system, subscribers means for making said line busy, a

relays for controlling said'circuit to operate said meter.

10. In a telephone system, a subscribers connector connector switches toestablish a connection with said line and establish a guarding potentialthereat, means for then operating another of said switches to test saidcalled line, and meaiis'in said connector switchresponsive to saidguarding potential for opf 'line, means for makingsaid li b t calls fromother subscribers, a meter for said erating'said meter.

11. In a telephone system, a subscribers line, a meter for said line,connector switches, connector switches to establish a talking circuitwith said line and establish a guarding potential thereat, means forthen operv ating another of said switches to test said called line, andmeans in said connector system, a subscribers; for making said line busywhen a connection is extended either to or from 1 'means for operatingone of said switchresponsive to said guarding potent al tor operatingsaid meter'over a circuit independent of said talking circuit.

12. In a telephone system, a. subscribers line, a meter for said line,connector switches,.means for operating one of said connectorswitchesto. establish a connection with said line and establish a guarding po-.tential thereat, means for then operating a nothei' of said switches totest said called line, and qu ck and slow relays in said connectorswitch responsive to said guarding "potential for operating said meter.

line, and quick and slow relays in said connector'switch responsive tosaid guarding potential for operating said meter over a circuitindependent ofsaid talking circuit.

14. In a telephone system, a subscribers a meter for said 'line,connector switches, means for operating each of said connectors to testand connect with said line, means for preventing the connection of morethan one of ,said connector switches with said line, and means in eachswitch for operating said meter momentarily when it connects withsa' dline while another of said switches-is connected thereto.

-15. In a telephone system, a subscribers line, means for making saidline busy to *zlls from other subscribers, a meter for said line, andmeans for operating said meter momentarily when another subscriberattempts to establish a connection with said busy line. V i

16. Ina telephone system, a subscribers .line', n eans formaking saidline busy to calls "from other subscribers, a meter for said 'j-line,vand means for operating said meter niomentarily each time anothersubscriber attempts establish a "connection with said busy line. I

17. In ajtelephone system, a subscribers line, means formaking said linebusy, a meter for said line for registering the number oi calls made tosaid line when busy, a circuit for said meter, and quick and slow relaysfor momentarily controlling said circuit to operate said meter.

18. In a telephone system, a 'subscribers line, and electromagneticmeans for operating said meter when another subscriber attempts toestablish a connection with said busy line. i i

' 19. In a telephone system, a subscribers line, means "for 'making saidline busy to calls from ethersubscribers, a meter for said line, and acircuit for operating said meter each time another subscriber attemptsto establish a connection with said busy line.

20. In a telephone system, a subscribers line, means for making saidline busy to calls from other subscribers when a call is extended eitherto or from said line, a meter for said line, and a circuit for operatingsaid meter when another subscriber attempts to establish a connectionwith said busy line.

21. In a telephone system, a subscribers line, means for making saidline busy, a connector switch, means for operating said connector switchto test said subscribers line, a meter for said line, and a circuitcontrolled by said connector switch for operating said meter when theline is tested and found busy.

22. In a telephone system, 'a subscribers line, means for making saidline busy when a connection is extended either to or from said line, aconnector switch, means for operating said connector switch to test saidsulr-scribers line, a meter for said line, and a circuit controlled bysaid connector switch for operating said meter when the line is testedand found busy.

23. In a telephone system, a subscribers line, a meter for said line,connector switches, means for operating one of said connector switchesto establish a connection with said line and establish a guardingpotential thereat, means for then operating another of said switches totest said called line, and

a relay in said connector switch responsive to said guarding potentialfor operating said meter.

24. In a telephone system, a subscribers line, a meter for said line,connector switches, means for operating one of said connector switchesto establish a talking circuit with said line and establish a guard ingpotential thereat, means for then operating another of said switches totest said called line, and a relay in said connector switch responsiveto said guarding potential for operating said meter over a circuitindependent of said talking circuit.

25. In a telephone system, a subscribers line, a meter for said line,connector switches, means for operating each of said connectors to testand connect with said line, means for preventing the connection of morethan one of said connector switches with said line, and a relay in eachswitch for operating said meter momentarily when it connects with saidline while another of said switches is connected thereto.

26. In a telephone system, a subscribers line, means for making saidline busy, a meter for said line, means for operating said meter whensaid line is called while busy.

Signed by me at Chicago, Cook county, Illinois, this 17th day ofDecember, 1917.

TALBOT G. MARTIN.

